# ---
# title: 1234. Replace the Substring for Balanced String
# id: problem1234
# author: Tian Jun
# date: 2020-10-31
# difficulty: Medium
# categories: Two Pointers, String
# link: <https://leetcode.com/problems/replace-the-substring-for-balanced-string/description/>
# hidden: true
# ---
# 
# You are given a string containing only 4 kinds of characters `'Q',` `'W', 'E'`
# and `'R'`.
# 
# A string is said to be  **balanced** _ _ if each of its characters appears
# `n/4` times where `n` is the length of the string.
# 
# Return the minimum length of the substring that can be replaced with **any**
# other string of the same length to make the original string `s`  **balanced**.
# 
# Return 0 if the string is already **balanced**.
# 
# 
# 
# **Example 1:**
# 
#     
#     
#     Input: s = "QWER"
#     Output: 0
#     Explanation: s is already balanced.
# 
# **Example 2:**
# 
#     
#     
#     Input: s = "QQWE"
#     Output: 1
#     Explanation: We need to replace a 'Q' to 'R', so that "RQWE" (or "QRWE") is balanced.
#     
# 
# **Example 3:**
# 
#     
#     
#     Input: s = "QQQW"
#     Output: 2
#     Explanation: We can replace the first "QQ" to "ER". 
#     
# 
# **Example 4:**
# 
#     
#     
#     Input: s = "QQQQ"
#     Output: 3
#     Explanation: We can replace the last 3 'Q' to make s = "QWER".
#     
# 
# 
# 
# **Constraints:**
# 
#   * `1 <= s.length <= 10^5`
#   * `s.length` is a multiple of `4`
#   * `s `contains only `'Q'`, `'W'`, `'E'` and `'R'`.
# 
# 
## @lc code=start
using LeetCode

## add your code here:
## @lc code=end
